Mysql优化策略

mysql 查询优化默认将左起不为数字的字符去除。

select '' = 0 from dual
union all
select '012wer' + 1 from dual
union all
select '124' + 1 from dual
union all
select 'sd31' + 1 from dual
union all
select '1sd12s' + 1 from dual;